This invention relates to a stepping motor driving circuit.
A stepping motor driving circuit is known which has a resistor or a zener diode connected in parallel with each coil of a stepping motor through a diode and functioning as a braking element. In the driving circuit using the resistor as a braking element, if a resistive value of the braking resistor is increased, a transient current which flows through the motor coil is rapidly attenuated at the final phase of each stepping motion, permitting the stepping motor to be stably driven by a high frequency drive pulse. In this case, however, it is possible to obtain only a small braking force. Where the motor is to be driven in a stepping fashion or a low frequency drive pulse is used, the motor will be driven with vibration in each step. If the resistive value of the braking resistor is decreased, the motor is smoothly driven, but it would be difficult to drive the motor with a high frequency drive signal.
Even in the driving circuit using the zener diode as the braking element, the frequency response characteristic of the motor is varied depending upon the magnitude of the zener voltage of the zener diode. Thus, the same problem as mentioned above arises.
In an electronic printer, etc. it is necessary to smoothly brake a stepping motor without causing vibration after it has been driven a required number of steps at high speed. The demand for such a stepping motor driving circuit has been growing steadily.